<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        let year=prompt("请输入年份")
        if(year%4==0 && year%100!=0  || year%400==0){
            alert(`${year}是闰年`)
        }
        else{
            alert(`${year}是平年`)
        }
    </script>    
</body>
</html>